1. Field
The present application relates to improved anti-smudging, gripping and shelf-life properties of products and surfaces through the use of low-ion plasma, superheated steam and gas system surface treatments as well as system combinations thereof.
2. Prior Art
There is currently a great need for bottles made of many materials, including plastics, for the containment and storage of consumer products. Plastic bottles often have labels on them which need to appear visually sharper and not smudge with use or age. Profitability is increased to a great extent when these conditions are achieved by making products more aesthetically pleasing and attractive as well as increasing the shelf-life of the bottle and its identifying label. Longer-lasting and visually sharper product labels allow older goods to stay on the shelf and remain for sale longer before replacement with fresher items. This would be especially important with non-perishable goods that, if marked with sharp and long-lasting labels, could be left on shelves indefinitely and still remain appealing and marketable to consumers. Older items, with still fresh-appearing labels, could be placed at the front of shelves and sold first. Costs associated with inventory and replacement of goods could thereby be substantially decreased.
Improvements in the physical properties of bottles are vital as well. Surface treatments are needed that can beneficially affect properties such as hardness, fatigue, creep, stickiness, gripability and the reactivity of a bottle's material. Often the transparency of a bottle is impaired by the presence of a wax or glue coating that is applied during processing. Methods are needed to remove the wax or glue without damaging labels if present; thereby making a surface that is matte, due to the presence of glue, transparent. Alternatively, a system is needed to create a matte finish, if desired, on bottles directly or in a manner that does not disturb labels, lettering or bar codes. Bottle or container surfaces often need to be cleaned before the application of labels as well.
Surface heat treatment using an open flame as the heat source is the present solution for the meeting of many of the above goals. Flame treatment is the current industry standard for surface cleaning of bottles prior to application of items such as chemical etch/photo etch/screened nameplates, pressure sensitive labels and decals, UID and mil-spec labeling, serialization and bar-code identification, specialty engravings, large-format digital and screen printing and specialty food and packaging labels. Flame is also required for heat transferred decals which may display abstract design elements resembling, for example, henna tattoo artwork. Flame curing is needed for labels, produced by DI-NA-CAL®-brand heat transfer labels, for example, which are formulated with a protective lacquer and, sometimes, a custom-designed adhesive print coat. Examples of methods and processes using flame to prepare and alter surfaces of bottles for application and/or preservation of labels and direct printing on a surface include U.S. Pat. No. 6,991,261 by Dronzek, Jr., et al., U.S. Pat. No. 6,939,602 by McGee, et al., U.S. Pat. No. 6,616,786 by Blom, et al., U.S. Pat. No. 6,513,435 by Detzner, U.S. Pat. No. 6,086,991 by Hubbard, et al., U.S. Pat. No. 5,925,208 and U.S. Pat. No. 5,711,839 by Dronzek, Jr., et al. and U.S. Pat. No. 5,085,034 by Haas.
As an alternative to open flame as a heat source, U.S. Pat. No. 6,013,333 by Carson, et al., and U.S. Pat. No. 6,086,991 by Hubbard, et al. suggest the use of plasma. This plasma, however, is not low-ion plasma, which can be defined as plasma with an ion percentage by volume of 2% or less. Upon application, ions in the plasma have been found to have a beneficial impact on surface properties. Plasma with low-ion content may be generated by the devices of U.S. Pat. No. 5,963,709 by Staples, et al. and U.S. Pat. No. 6,816,671 by Reddy, et al. Small amounts of thermal plasma may be created in very high temperature environments employing high temperature heating elements composed of materials such as molybdenum, tungsten and molybdenum disilicide materials. Plasma can also generated by RF means, as illustrated by U.S. Pat. No. 3,648,015 by Fairbairn, which relates to cold plasma, U.S. Pat. Nos. 5,403,453, 5,387,842, 5,414,324, 5,456,972 by Roth, et al., U.S. Pat. Nos. 5,669,583, 5,938,854, 6,146,724 by Roth and U.S. Pat. No. 6,245,132 by Feldman et al. Not all techniques can produce air plasma at normal pressures and not all techniques, except for U.S. Pat. Nos. 5,963,709 and 6,816,671, can be considered to produce substantial heat delivered simultaneously with hot gas. The plasma recombination leads to heat but only generally at a recombining surface.
Superheated steam, which is often used synonymously with saturated and super-saturated steam, although there may be some differences, may be generated in a number of ways for various purposes. U.S. Pat. No. 6,900,421 by Varma is directed to a sterilizing apparatus using microwave heating for the generation of superheated steam. U.S. Pat. No. 6,880,491 by Reiner, et al. concerns the generation of superheated steam using hydrogen peroxide and a combustible fluid, wherein the combustion process decomposes the hydrogen peroxide to produce superheated steam. U.S. Pat. No. 7,115,845 by Nomura, et al. consists of a superheated steam generator that uses electromagnetic induction to produce the superheated steam. Here, in one embodiment of the present application, the superheated steam generator may be comprised of a heater such as the coil-in-coil type disclosed in U.S. Publication No. 2007/0145038 by Vissa, et al., which overcomes problems associated with the relationship of Psat and Tsat. The heater may also be of the type disclosed in U.S. Publication No. 2010/129157 by Reddy, et al. In the present patent application, the use of superheated steam, alone or in conjunction with low-ion plasma has been shown to improve surface and bulk properties of products exposed to it.
When an open flame is applied directly to a bottle to remove glue and wax or to improve surface and bulk properties, a number of disadvantages are presented including:                a) Flame treatment processes are environmentally harmful. They produce CO2 and SO2 soot. Typically, 20,000 BTU natural gas burners produce about 22 moles of greenhouse gasses per hour (1025 molecules per hour). Combustion products from fuels containing carbon also often produce very toxic gasses such as carbon monoxide (CO). Such a method is not environmentally friendly or a green technology.        b) Combustion gas input is used which requires plumbing for delivery and application adding to the cost of set-up and operation.        c) Combustion flame has a narrow area of impact and is therefore its application is non-uniform. To attain the needed uniformity many burners may be needed, adding to the cost and complexity of the process.        d) There is a high potential for explosion due to the presence of combustible gas. Combustion flame is commonly associated with combustion emissions and fire hazards. Employees must be adequately trained and be provided with protective equipment.        e) Flames are inherently energy inefficient with, typically, about 10% of the energy being used in directed flame operations. Most of the energy is not applied to the product.        f) There is a lack of precise control from combustion flames leading to lack of optimization of processes.        g) Flame combustion produces high noise. It also requires the added cost of hearing protection for workers and possible specialized placement and sound insulation of process equipment.        h) There is a continuous requirement for consumables such as reactant gasses leading to increased costs and decreases in profitability. Safety and environmental clean-up costs are incurred.        
It is therefore apparent that the current technology is not meeting the above stated goals in an environmentally safe, energy efficient or cost effective manner. With the increase in potentially disastrous effects associated with global warming and the volatile economy, new devices and methods are needed to address these effects, where the present flame treatment technology does not, in regards to improvement of anti-smudging, gripping and shelf-life properties of products and surfaces.